Continuous Sheet Tension Control for Absorbent Article Manufacturing
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Solution Overview
Problem
In the manufacturing of disposable diapers, the position adjustment of continuous sheets in the direction of transport can cause contraction or stretching, leading to deviations in processing positions, resulting in inappropriate pitch and positional inaccuracies.
Innovation Solution
A method and apparatus that involve detecting the trace of processing on the continuous sheet downstream from the processing position and adjusting the tension upstream to maintain appropriate positions, with the adjustment processing position located downstream from the processing position, ensuring accurate positioning and reducing deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If position adjustment device adjusts positions of end portions in CD direction to increase width dimension, then width dimension is improved, but continuous sheet contracts in direction of transport causing processing position deviation
Solution Approach 1:
A detection device detects the actual position of processed portions on the continuous sheet, and this detection result is fed back to a tension adjustment device. The tension adjustment device then adjusts the tension of the continuous sheet in the direction of transport based on the detected position, creating a closed-loop feedback system that compensates for position deviations caused by CD-direction adjustments.
Solution Approach 2:
The invention changes the tension parameter of the continuous sheet in the direction of transport to compensate for contraction or stretch. By dynamically adjusting the tension based on detection results, the system counteracts the unwanted dimensional changes that occur when adjusting the width dimension through CD-direction position adjustment.
2Measurement precision
If position adjustment device applies force in CD direction to adjust end portion positions, then positioning accuracy in CD direction is improved, but contraction or stretch occurs in direction of transport
Solution Approach 1:
The tension adjustment device applies a counteracting force in the direction of transport to compensate for the contraction or stretch caused by CD-direction position adjustment. The detection device identifies the extent of position deviation, and the tension adjustment applies an opposing tension to restore the correct length and positioning in the transport direction.
Solution Approach 2:
The system dynamically changes the tension parameter in the direction of transport to offset the unwanted length changes. By adjusting the tension based on real-time detection, the system maintains the correct dimensional relationships even as CD-direction positioning is modified.
3Productivity
If processing positions are set at fixed intervals in direction of transport, then production efficiency is improved, but position deviation occurs due to sheet contraction or stretch
Solution Approach 1:
The invention transitions from static fixed-interval processing to a dynamic system where processing positions are continuously adjusted based on real-time detection. The tension adjustment device dynamically modifies the sheet tension to compensate for contraction or stretch, allowing the system to maintain both high productivity and precise positioning despite variations in sheet dimensions.
Solution Approach 2:
The detection device continuously monitors the actual positions of processed portions, and this feedback is used to adjust the tension in real-time. This enables the system to maintain accurate processing intervals even when the sheet undergoes contraction or stretch during CD-direction position adjustment, preserving both productivity and precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces positional deviations and maintains accurate processing positions by dynamically adjusting tension based on detection results, improving the precision and efficiency of the manufacturing process.
Implementation Method 1
a detecting device that detects a trace of processing left on the continuous sheet, at a detection processing position downstream in the direction of transport from the processing position and the adjustment processing position
Implementation Method 2
the supplying section being configured to adjust, based on the detection result, a tension in the direction of transport of the continuous sheet
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
Included are a supplying step of transferring and supplying a continuous sheet (3a) to a processing section (L3aK) by transporting the sheet (3a) in a direction of transport that conforms to a continuous direction in which the sheet (3a) continues; a processing step of performing processing onto portions of the sheet (3a) at intervals in the direction of transport, at a processing position (P3a) in the direction of transport, using a processing device (34) in the processing section (L3aK), the portions each corresponding to an absorbent article 1; a position adjusting step of adjusting, in a CD direction, a position of an end portion (3ae) in the CD direction in the sheet (3a), the CD direction intersecting the direction of transport in the sheet (3a), the position adjusting step being performed at an adjustment processing position (P35) in the direction of transport; and a detecting step of detecting a trace of the processing left on the sheet (3a), at a detection processing position (P36) downstream in the direction of transport from the processing position (P3a) and the adjustment processing position (P35), and outputting a detection result. The supplying step includes adjusting, based on the detection result, a tension in the direction of transport of the sheet (3a) at a time of being transferred to the processing section (L3aK).